Making it easier to investigate jank and latency traces

Shortening Cuj<> to a more meaningful J<> for jank.

Using L<> for latency will make it easier to search for
Latency traces in trace tools. Using getNameOfAction() for
latencies in all places will simplify finding latencies in code.

Test: manual
Bug: 177018359
Change-Id: Ie3114e7d7f97e7950af19a014d06f5c632a607c3